Ideas for a NY's brunch when one guest is gluten-free and one is vegetarian but loves seafood?

For one of your gluten-free quiches, consider this recipe--http://food52.com/recipes/14244_quinoa_and_kale_crustless_quiche
I make it a lot, and frequently vary the cheeses (Gruyere and yogurt instead of cream cheese is my favorite combination). I also prefer spinach to the kale (and have used frozen spinach which makes it super easy).

Dang it...I must have clicked away..or something is wonky with the add answer. Well to sum up, my lost post. I like the Sushi idea, but Sashimi or a Poke might be easier to deploy.
A Gulf Coast Favorite is a "West Indies Salad". A layered vingared salad with lump crab meat and onions. That's it.
Normally served with saltines..but you could make cracker, and offer lettuce cups as an option. Best made the night before.
http://www.saveur.com/article/Recipes/West-Indies-Salad-

Wow! What great, creative answers! I can always rely on Sam for creativity and particularly like the cobbler idea--it's unexpected and cozy. SKK--love the crustless quiche suggestion. SparkleDiana--good idea. I'll report back. Thanks so much, all.

How do you feel about making sushi? You could set up a sushi making bar, so guests can roll their own sushi with whatever veggie or seafood ingredients they enjoy. There are GF tamari sauces to use in place of regular soy sauce. Everyone can customize and the activity is fun.

First of all, lucky friends! Love your idea of shrimp cocktail. Perfect.
The recipes I am recommending have been served at brunches and have gotten rave reviews from GF, vegans and carnivores alike!
http://food52.com/recipes/12680_dukkah_deviled_eggs
A brilliant crustless quiche - served this at brunch before my daughter's wedding last summer and everyone has asked for the recipe. Another benefit is you can prep ahead and bake the day of. And it tastes great at room temperature http://food52.com/recipes/14244_quinoa_and_kale_crustless_quiche
Two brilliant salads:
http://food52.com/recipes/4560_goat_cheese_caesar_salad_with_roasted_tomatoes_and_parmesan_crisp
http://food52.com/recipes/8768_apple_harvest_salad
Desserts: Chefjune has a wonderful sorbet you don't need a ice cream maker for
http://food52.com/recipes/371_quick_strawberry_sherbet
Now for those not GF and vegetarians, this is an amazing pasta sauce - brunch without a pasta is almost unthinkable - http://food52.com/recipes/13722_marcella_hazans_tomato_sauce_with_onion_and_butter
Hope this helps! Let us know what you decide.
One more thing regarding dessert - I have been serving individual pieces of great chocolate for dessert and people have really enjoyed it. Also it is easy.

Bloody mary bar..with pickled green beans, shrimp, beef sticks NOT slim jims they taste like newsprint now--Wisconsin best is a good brand, celery, pickled okra, carrot sticks, olives, cocktail onions...etc..etc.
And a salad (bread and butter on the side board).
Steamed crab legs would fit. And maybe a egg dish like a crustless quich with veggies. Latkes with sour cream and apple option. Or hash browns. Heck---take short cut and use ore-idea shredded hash brown to make the latkes. (g). Or a potato anna.
Mimosas would be another brunch 'day after' drink option the peach or orange juice with soda water could do double duty for non-drinkers.

Desert how about a cobbler? Apple cobbler or peach cobbler (not in season tho). One quick trick for desert is simply banana sliced on the bias, topped with sugar and use a blow torch to make a cracking crust like a burlee, serve the slices with ice cream.